[NTLK] Can the Newton's ARM processor ever be upgraded?

[Matthias Melcher]

> On 3. Dec 2025, at 16:03, Tom <tom+newtontalk at falkensweb.com> wrote:
> 
> On Saturday, 29 November 2025 23:17:22 Greenwich Mean Time Doug wrote:
>> Spitballing… could an Arduino or RaspberryPi or some powerful PLC ever
>> be programmed to substitute for the StrongArm? I could see the core
>> code blazing, but having its serial communication throttled
>> appropriately.
> 
> 
> There's a project doing this for the custom ROM chips in the Vic 20, Commodore 64 etc :
> https://onerom.org/[1]
> And was recently on a podcast talking about all the neat tricks you can do (wifi ROM updates, bank switching, ....):
> https://hackaday.com/2025/10/08/floss-weekly-episode-850-one-rom-to-rule-them-all/[2]
> 
> At least, it's a similar-ish era.
> 
> -- 
> Tom
> MessagePad 110, 2100 owner and, in case it's not obvious, geek.

That is quite an amazing project!

They don't replace the CPU thoug, they use a second CPU to emulate a ROM. The 6502 in the C64 runs at 1MHz. Whenever it requests a byte from the ROM, the PR2350 CPU sees the address lines, looks up the byte in ints own memory, and writes it to the data bus. It can do that fast enough, running at 150MHz. 

The RP2350 CPU does not replace the 6502 in the C64. The C64 still runs at the original speed.

With the second core, the PR2350 can handle a USB port that is used by another computer to update ROM images.